1. Field of the Invention
The invention relates to a vehicle capable of traveling by using power of at least one of an engine and a motor and, more particularly, to a vehicle provided with a rotary electric machine providing a cranking torque to act on an engine by generating electric power.
2. Description of Related Art
Japanese Patent Application Publication No. 2007-131103 (JP 2007-131103 A) discloses a hybrid vehicle provided with an engine, a motor that is connected to a drive wheel, and a generator that is connected to the engine and the motor via a planetary gear device. The hybrid vehicle is capable of motor traveling in which the hybrid vehicle travels by using power of the motor in a state where the engine is stopped. During the motor traveling, the generator is rotated in the direction opposite to a rotation direction of the motor as the motor rotates. When the engine is started during the motor traveling, the generator generates electric power so that a cranking torque acts on the engine.
The electric power that is generated by the generator during cranking is accepted by a vehicle battery. The absolute value of a rotation speed of the generator during the motor traveling increases as a rotation speed of the motor (that is, a vehicle speed) increases. Accordingly, the electric power that is generated by the generator during the cranking increases as the vehicle speed increases and is highly likely to exceed electric power that can be accepted by the battery. In view of this, an upper limit vehicle speed for the motor traveling is set according to the electric power that can be accepted by the battery in the hybrid vehicle and the engine is promptly started (cranked) in a case where the vehicle speed exceeds the upper limit vehicle speed during the motor traveling. In this manner, the electric power that is input into the battery during the cranking exceeding the electric power that can be accepted by the battery can be suppressed.